Corruption effects do stack if you have the same effect on more than one item, but the duration of procs does not increase. On-equip effects include passives, procs, and unique effects.

Do the same corruptions stack?

Note that when using more than one of the same Corruption, even different tiers, the effect/benefit (damage, statistical gains, etc) stack while durations and proc rates remain unchanged. ... Corruption can randomly proc on any Season 4 item, except Trinkets cannot Corrupt!

Should I cleanse corrupted gear wow?

If the positive affix is mediocre, you may want to cleanse it so you don't have to deal with the negative aspect of Corruption. If you don't want to deal with the system at all, you can simply cleanse every piece of Corrupted gear that you get.